I came across the sentence
Environmental considerations and Australia’s absorptive capacity are conspicuously absent, as is the investment infrastructure required to provide services to the growing population.
Could it have been
Environmental considerations and Australia’s absorptive capacity are conspicuously absent, as the investment infrastructure is required to provide services to the growing population?
Why is this grammar construction used here?
Logically, the straightforward form of the sentence would be
Environmental considerations and Australia’s absorptive capacity are conspicuously absent, as the investment infrastructure required to provide services to the growing population is.
But when you have a very long subject (the investment infrastructure required to provide services to the growing population) and a short verb phrase (is) in a subordinate clause, it can be difficult for the hearer or reader to parse, and English allows you to swap them: this process is called extraposition, and gives you the original sentence
Environmental considerations and Australia’s absorptive capacity are conspicuously absent, as is the investment infrastructure required to provide services to the growing population.
When the subject itself has an embedded relative clause, it is also possible to extrapose only that clause. So if the subject were the fuller the investment infrastructure that is required to provide services to the growing population, you could extrapose that relative clause:
Environmental considerations and Australia’s absorptive capacity are conspicuously absent, as the investment infrastructure is that is required to provide services to the growing population.
In principle, you can do this even with the "reduced relative clause" required to provide services to the growing population, but as others have pointed out, the result (your second sentence) has another, more obvious, reading with a different structure. But in speech, and with a comma after "is", I can imagine somebody saying your second sentence.
I agree with others that this "as is" has become a set phrase, but I think in this case it is completely analysable and doesn't have a special meaning.
This sentence puts together three parallel ideas:
- Environmental considerations are conspicuously absent
- Australia’s absorptive capacity is conspicuously absent
- The investment infrastructure required to provide services to the growing population is conspicuously absent
The first two ideas are put in parallel with a simple and. The third idea is put in parallel using the conjunction as with the meaning in the same way. here is another example of this usage:
As is often the case with children, Amy was completely better by the time the doctor arrived
They could all have been paralleled using and, but the author chose for reasons of literary style to use a different method with the last item.
In your alternative sentence, as now takes on the meaning because, which suggests a causality that does not exist in the original sentence.
Could it have been as the investment infrastructure is required to [...]?
No. "As is" is a fixed phrase. The "as-is" part of the sentence means:
The investment infrastructure required to provide services to the growing population is also conspicuously absent
In this case, "as is" means something like "as well as"; it introduces another item which has the same property (being conspicuously absent).
Moving is as you suggested ends up with this sentence:
"Environmental considerations and Australia’s absorptive capacity are conspicuously absent, as the investment infrastructure is required to provide services to the growing population".
This version means something different. This version means that Environmental considerations and Australia's absorptive capacity are absent because investment infrastructure is required.
